Car power source apparatus

ABSTRACT

A case ( 20 ) of each battery cell ( 1 ) houses a current interrupt device ( 30 ) that cuts-off current when internal pressure exceeds a set pressure. The case has a rectangular outline with a pair of opposing planar surfaces ( 20 A). An electrode unit ( 10 ), which is a stack of positive and negative electrode plates ( 10 A) with intervening separators ( 10 C), and the current interrupt device are disposed between the pair of opposing planar surfaces. A plurality of battery cells is stacked with opposing planar surfaces opposite each other to form a battery block ( 2 ). The power source apparatus has a pair of endplates ( 4 ) disposed at the ends of the battery block, the pair of endplates is connected by connecting components ( 5 ), and the pair of endplates holds the battery cells in the stacked configuration applying pressure in a direction perpendicular to the opposing planar surfaces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a car power source apparatus thatsupplies power to a motor that drives the vehicle.

2. Description of the Related Art

To increase power supplied to the motor that drives a vehicle, the carpower source apparatus increases output voltage of a battery block byconnecting many rechargeable batteries in series to form that batteryblock. This car power source apparatus is discharged to supply power tothe motor when the vehicle is driven, and is charged by a generatorduring regenerative braking of the vehicle. Battery discharge currentdetermines the driving torque of the motor, and battery charging currentdetermines the braking performance of the regenerative braking system.Therefore, to increase the driving torque of the motor that acceleratesthe vehicle, it is necessary to increase battery discharge current. Toimprove regenerative braking, charging at high currents is required. Asa result, batteries of the car power source apparatus are charged anddischarged with high currents. To improve the safety of batteriescharged and discharged with high currents, a battery housing a currentinterrupt device has been developed to cut-off current when internalbattery pressure becomes abnormally high. (Refer to Japanese Laid-OpenPatent Publication No. 2006-128104.)

The battery described above can improve safety by cutting-off currentwhen internal pressure becomes abnormally high. However, this batteryhas the drawback that the current interrupt device can be damaged byvibration to cut-off current and make the battery unusable. This isbecause vehicle vibration can cause the electrodes to move inside thebattery case putting a load on the connection region of the currentinterrupt device. The connection region of the current interrupt deviceis designed with a connection strength that results in separation andcurrent cut-off when internal battery pressure rises abnormally. If theconnection region is too strong, it will be unable to separate andcut-off current when internal pressure rises abnormally. Consequently,there are constraints on the strength of the connection region, and ithas the drawback that it separates easily with vibration. In particular,for batteries installed on-board a vehicle, vehicle vibration duringdriving cannot be eliminated, and the current interrupt device cancut-off current due to the vehicle vibration. If the current interruptdevice of a battery in a car power source apparatus cuts-off currentduring driving, the motor will stop suddenly and it will be impossibleto maintain smooth driving. Even worse, this battery has the drawbackthat in a pure electric automobile, the vehicle becomes completelyunable to drive.

The present invention was developed with the object of correcting thedrawbacks described above. Thus, it is an important object of thepresent invention to provide a car power source apparatus that improvesbattery safety with a current interrupt device housed in each battery tocut-off current when internal battery pressure rises abnormally, whileeffectively preventing current interrupt device cut-off due to vehiclevibration.

SUMMARY OF THE INVENTION

The car power source apparatus of the present invention is provided witha current interrupt device housed in a case of each battery cell thatdeforms to separate a connection point and cut-off current when batterycell internal pressure becomes greater than a set pressure, and a highvoltage battery having a plurality of series or parallel-connectedbattery cells with current interrupt devices connected to the electrodeterminals. A battery cell case has a rectangular outline and a pair ofopposing planar surfaces. An electrode unit that is a stack of positiveand negative electrode plates with intervening separators, and a currentinterrupt device are disposed between the pair of opposing planarsurfaces. Further, a plurality of battery cells is stacked with opposingplanar surfaces opposite each other to form a battery block. The carpower source apparatus has a pair of endplates disposed at both ends ofthe battery block, and connecting components that connect the pair ofendplates. The battery block is held with pressure applied in adirection perpendicular to the opposing planar surfaces of the stack ofbattery cells between the pair of endplates.

The car power source apparatus described above realizes the extremelyimportant characteristic for a car power source apparatus that batterycell safety is improved by housing a current interrupt device in eachbattery cell to cut-off current when internal battery pressure risesabnormally, and current interrupt device cut-off due to vehiclevibration is effectively prevented. This is because the case of eachbattery cell housing a current interrupt device has a pair of opposingplanar surfaces of rectangular shape; and an electrode unit that is astack of positive and negative electrode plates with interveningseparators, and a current interrupt device are disposed between thatpair of opposing planar surfaces. Further, a plurality of battery cellsare stacked with opposing planar surfaces opposite each other to form abattery block, a pair of endplates is disposed at both ends of thebattery block, the two endplates are connected by connecting components,and the stack of battery cells held by the endplates is retained withpressure applied in a direction perpendicular to the opposing planarsurfaces. In this power source apparatus, an electrode unit and currentinterrupt device are disposed between the opposing planar surfaces ofeach battery cell, a plurality of these battery cells is stacked to forma battery block, and pressure is applied to both ends of the batteryblock by the endplates to compress the opposing planar surfaces of thebattery cell cases. Consequently, the electrode unit and currentinterrupt device of each battery cell are maintained in a compressedstate by the opposing planar surfaces, and the electrode unit andcurrent interrupt device do not move due to vibration. Therefore,disconnection of the connection region and current cut-off are preventedby the electrode unit and current interrupt device moving together.

In the car power source apparatus of the present invention, a currentinterrupt device can be provided with a deformable metal plate thatdeforms with battery cell internal pressure, and connection metal thatlocally connects to the deformable metal plate for electricalconnection. When battery cell internal pressure becomes greater than aset pressure, the deformable metal plate deforms and separates from theconnection metal to cut-off current. This car power source apparatus canreliably cut-off current when internal battery cell pressure rises abovethe set pressure while the current interrupt device has a simplestructure.

In the car power source apparatus of the present invention, thedeformable metal plate can be a diaphragm curved in an arch-shape, andthe peak of the arch-shaped diaphragm can be welded for electricalconnection to the connection metal. This car power source apparatus hasthe characteristic that since the arch-shaped diaphragm deforms withinternal battery cell pressure to cut-off current, current can bereliably cut-off with abnormal internal pressure rise and the cut-offstate can be maintained.

In the car power source apparatus of the present invention, thediaphragm can be connected to an electrode terminal, and the connectionmetal can be connected to an electrode tab that is connected to anelectrode plate. This power source apparatus has the characteristic thatby housing battery cell contents in a case that retains the contents inan immovable fashion sandwiched between opposing planar surfaces,separation of the diaphragm connection region can be reliably prevented.This is because retaining the diaphragm with an electrode terminal andretaining the electrode unit by sandwiching it between opposing planarsurfaces of the case allows prevention of relative movement between thediaphragm and the connection metal, which is connected to the electrodetab.

In the car power source apparatus of the present invention, the positiveand negative electrode plates and intervening separators can stacked andwound into a spiral-shaped electrode unit having planar sections andU-shaped rounded sections. This electrode unit can be held in a batterycell case with planar sections oriented parallel to the opposing planarsurfaces of the case. In this car power source apparatus, the planarsections of the electrode unit can be compressed in the electrodestacking direction and retained in a stationary state by the opposingplanar surfaces of the case, while the electrode unit can be efficientlyfabricated by winding it in a spiral-shape. Consequently, separation ofthe current interrupt device connection region due to vehicle vibrationcan be reliably prevented.

In the car power source apparatus of the present invention, the case canbe a metal case, and insulating material can be provided between theinside surfaces of the case and the conducting regions of the currentinterrupt device.

The car power source apparatus of the present invention can be providedwith insulating material between the inside surfaces of the case andconducting regions of the electrode unit.

In the car power source apparatus of the present invention, aninsulating layer can be provided on the inside surfaces of the case.This power source apparatus can prevent electrical contact between thecase and the current interrupt device or the electrode unit whileapplying pressure to opposing planar surfaces of the case to retain theelectrode unit and current interrupt device in a stationary fashion.Therefore, the case can be retained with pressure applied to theopposing planar surfaces, and detrimental effects such as battery cellinternal short circuits can be prevented.

In the car power source apparatus of the present invention, a currentinterrupt device is housed in the upper section of each battery cell,upper and lower sections of the endplates are joined by the connectingcomponents, and upper sections of the pair of endplates are pulledtogether by the connecting components to retain the battery cells withpressure applied to their upper sections. In this car power sourceapparatus, upper sections of the battery cell cases housing currentinterrupt devices can be retained with pressure applied by the endplatesvia the upper connecting components. In addition, lower sections of thebattery cell cases housing electrode units can be retained with pressureapplied by the endplates via the lower connecting components. Thisallows both the current interrupt device and the electrode unit to beheld in a stationary manner inside the case of each battery cell.Therefore, this power source apparatus has the characteristic thatseparation of a current interrupt device connection region due tovehicle vibration can be more reliably prevented.

In the car power source apparatus of the present invention, the currentinterrupt device can be connected between an electrode terminal and anelectrode tab connected to the electrode unit. This car power sourceapparatus can prevent any movement due to electrode tab vibration byreliably retaining the electrode unit and current interrupt device withpressure applied to opposing planar surfaces of the case. Therefore,separation of the connection region of the current interrupt device,which is connected to an electrode tab, can be effectively prevented.The above and further objects of the present invention as well as thefeatures thereof will become more apparent from the following detaileddescription to be made in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a car power source apparatus for anembodiment of the present invention;

FIG. 2 is a perspective view showing the layout of high voltagebatteries in the car power source apparatus shown in FIG. 1;

FIG. 3 is a perspective view of a high voltage battery shown in FIG. 2;

FIG. 4 is an exploded perspective view of the high voltage battery shownin FIG. 3;

FIG. 5 is a side view of the high voltage battery shown in FIG. 3;

FIG. 6 is a perspective view of a battery cell;

FIG. 7 is a vertical cross-sectional view of the battery cell shown inFIG. 6;

FIG. 8 is a lateral cross-sectional view of the battery cell shown inFIG. 6;

FIG. 9 is an abbreviated cross-sectional view showing one example of acurrent interrupt device;

FIG. 10 is an abbreviated cross-sectional view showing the currentinterrupt device of FIG. 9 in the current cut-off state; and

FIG. 11 is an abbreviated cross-sectional view showing another exampleof a current interrupt device.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

The car power source apparatus of the present invention is primarilysuitable as a power source apparatus for use on-board an electricallydriven vehicle such as a hybrid car or electric automobile to supplypower to a driving motor to drive the vehicle.

The car power source apparatus of FIGS. 1-5 is provided with a highvoltage battery 9 that has a plurality of rechargeable battery cells 1connected in series to increase output voltage. The power sourceapparatus of FIGS. 1 and 2 is provided with four high voltage batteries9. A high voltage battery 9 preferably has all battery cells 1 connectedin series to increase output voltage. However, a high voltage batterycan also have a plurality of battery cells connected in parallel andthose parallel connected battery cells can in turn be connected inseries.

The rechargeable battery cells 1 are lithium ion batteries. However, anybatteries that can be recharged, such as nickel hydride batteries ornickel cadmium batteries can be used as battery cells. As shown in FIGS.7 and 8, a battery cell 1 has an electrode unit 10, which is a stack ofpositive and negative electrode plates 10A with intervening separators100, contained in a case 20 and filled with electrolyte solution. Inaddition, a battery cell 1 houses a current interrupt device 30 in thecase 20. If battery cell internal pressure exceeds a set pressure, thecurrent interrupt device 30 deforms to separate a connection point andcut-off current. FIGS. 9 and 10 are abbreviated cross-section viewsshowing a specific example of a current interrupt device 30. In thebattery cell 1 of these figures, the current interrupt device 30 isconnected between an electrode tab 31 connected to the electrode unit 10and an electrode terminal 32 mounted on the sealing plate 22. A currentinterrupt device 30 in the ON state connects the electrode tab 31 to theelectrode terminal 32. If the current interrupt device switches to theOFF state, the electrode tab 31 becomes disconnected from the electrodeterminal 32 and battery cell current is cut-off.

FIG. 9 shows the current interrupt device 30 in the non-cut-off state,and FIG. 10 shows it in the cut-off state. The current interrupt device30 shown in these and other figures is provided with a deformable metalplate 33 that deforms with battery cell 1 internal pressure, andconnection metal 34 locally welded to the deformable metal plate 33 forelectrical connection. When battery cell internal pressure becomesgreater than the set pressure, the current interrupt device 30deformable metal plate 33 deforms due to pressure and separates from theconnection metal 34 to cut-off current as shown in the sequence fromFIG. 9 to FIG. 10.

The current interrupt device 30 deformable metal plate 33 is a diaphragm35 formed to curve in an arch-shape. This diaphragm 35 is connected atits periphery to the lower end of an electrode terminal 32 that ismounted on the sealing plate 22. The peak of the arch-shaped diaphragm35 is welded to the connection metal 34 for electrical connection. Theconnection metal 34 is connected to an electrode tab 31. This currentinterrupt device 30 is in the ON state with the diaphragm 35 connectedto the connection metal 34. Further, the diaphragm 35 and connectionmetal 34 of the current interrupt device 30 are contained inside aninner case 36 made of insulating material such as plastic.

In FIGS. 9 and 10, the inner case 36 allows the bottom surface of thediaphragm 35 to associate with the inside of the battery cell 1, whilethe top surface of the diaphragm 35 is sealed in an air-tight fashion.Battery cell internal pressure does not act on the air-tight sealed topsurface of the diaphragm 35. In this configuration of the currentinterrupt device 30, battery cell internal pressure acts on the bottomsurface of the diaphragm 35 to push the diaphragm 35 upwards. The upwardforce on the diaphragm 35 increases in proportion to the battery cellinternal pressure. Consequently, when internal battery cell pressurerises, the diaphragm 35 is pushed upwards and deforms from the stateshown in FIG. 9 to that shown in FIG. 10. The diaphragm 35 deformed tothe state shown in FIG. 10 is separated from the connection metal 34 andbattery cell current is cut-off. The deformed diaphragm 35 in the stateshown in FIG. 10 is maintained in this state, which is the currentcut-off state or the OFF state, and is not restored to the ON state.Consequently, if battery cell internal pressure exceeds the setpressure, the current interrupt device 30 cuts-off current andthereafter is maintained in the current cut-off state.

As shown in FIG. 11, the current interrupt device 40 includes adiaphragm 35, which is a deformable metal plate 33. The plate 33 can beattached in an air-tight fashion to a cover plate 47 to seal-off theupper surface of the diaphragm 35. In a current interrupt device 40 ofthis configuration, the cover plate 47 and diaphragm 35 are formed in adisk shape by welding them together at their peripheries or by crimpingtheir peripheries together in an air-tight fashion. The cover plate 47is provided with a step flange 47A around its periphery that protrudestowards the diaphragm 35, and the periphery of the diaphragm 35 isattached to this step flange 47A. The projecting peak region of thediaphragm 35 is connected to the connection metal 34 by welding. Wheninternal battery cell pressure is lower than the set pressure, thecurrent interrupt device 40 has its diaphragm 35 connected to theconnection metal 34 and is in the ON state. Specifically, the ON stateallows battery current to flow. When the pressure of the internalbattery cell 1 rises abnormally and exceeds the set pressure, thediaphragm 35 deforms to the position shown by the broken lines of FIG.11 and separates from the connection metal 34 to cut-off current. Inthis state, the diaphragm 35 is maintained in the upward curvedconfiguration. As shown in FIG. 11, for a current interrupt device 40with one surface of diaphragm 35 sealed-off in an air-tight fashion by acover plate 47, it is unnecessary for the inner case 46 to seal-off theupper surface of the diaphragm 35 in an air-tight fashion and thestructure of the inner case 46 can be simplified.

The current interrupt device 30, 40 is connected between an electrodeterminal 32 that is mounted on the sealing plate 22 and the electrodeunit 10 housed inside the case 20. Therefore, if the current interruptdevice 30, 40 or the electrode unit 10 moves inside the case 20 due to acondition such as vibration, excessive force can be applied to theconnection region of the deformable metal plate diaphragm 35 to theconnection metal 34 with the detrimental result that the connectionregion weld can separate.

As shown in FIGS. 6 and 8, to prevent this detrimental effect, a batterycell 1 has a rectangular outline with a pair of opposing planar surfaces20A, and the electrode unit 10 and current interrupt device 30 arecontained between the pair of opposing planar surfaces 20A to form arectangular battery cell 1. In addition, a plurality of these batterycells 1 is stacked with opposing planar surfaces 20A opposite each otherto form a battery block 2, and the battery block 2 is held with pressureapplied by the endplates 5 at both ends of the battery block 2. For abattery cell 1 retained in this manner, opposing planar surfaces 20A arepressed towards each other and the electrode unit 10 and currentinterrupt device 30 contained inside are held in a stationary mannerthat does not vibrate.

A battery cell case 20 is made from metal or is molded from hardplastic. A metal case 20 is made from aluminum, aluminum alloy, iron,steel, or other iron alloy. A metal case 20 is made by pressingdeformable metal plate in the shape of a cylinder with a closed bottomto form an external case 21, and by closing off the open region of thisexternal case 21 in an air-tight fashion with a sealing plate 22. Thesealing plate 22 is attached to the external case 21 by a method such aslaser welding. The external case 21 is formed in a rectangularcylindrical shape with rectangular opposing planar surfaces 20A on bothsides, or it is formed in a cylindrical shape with opposing planarsurfaces on both sides connected by U-shaped rounded surfaces. Positiveand negative electrode terminals 32 are mounted to pass through themetal sealing plate 22 in a manner that is insulating and air-tight.

By reducing battery cell case 20 thickness (D) to width (W) ratio(D)/(W), the internally housed electrode unit 10 and current interruptdevice 20 can be compressed by opposing planar surfaces 20A on bothsides and held in a manner that is more difficult to move. Consequently,the case thickness (D) to width (W) ratio (D)/(W) is made, for example,less than or equal to 1/2, preferably less than or equal to 1/3, andmore preferably less than or equal to 1/4. However, if the thickness (D)to width (W) ratio (D)/(W) is made too small, the case 20 will be toothin and battery capacity efficiency will drop off. Therefore, thickness(D) to width (W) ratio (D)/(W) is made, for example, greater than orequal to 1/50, preferably greater than or equal to 1/40, and morepreferably greater than or equal to 1/30.

As shown in FIGS. 7-11, a metal case 20X is provided with insulatingmaterial 39, 49 between the inside surfaces of the case and theconducting regions 38, 48 of the current interrupt device 30, 40 toestablish a structure that avoids contact of the metal case 20X with theconducting regions 38, 48 of the current interrupt device 30, 40. In thebattery cell 1, the current interrupt device 30, 40 is contained in aninsulating plastic inner case 36, 46, and the inner case 36, 46 servesas insulating material 39, 49 to insulate the conducting regions 38, 48of the current interrupt device 30, 40 from the metal case 20X. Further,insulating material 29 is provided between inside surfaces of the metalcase 20X and conducting regions of the electrode unit 10 to establish aconfiguration that avoids contact between electrode plates 10A, whichare the conducting regions of the electrode unit 10, and the metal case20X. Insulating material of the electrode unit 10 can be insulatingseparators 10C that are stacked with the electrode unit 10, aninsulating layer 28 laminated on inside surfaces of the case 20, or acoating on the inside of the case 20 to form an insulating layer 28.

As shown in FIG. 8, the electrode unit 10 is made by rolling positiveand negative electrode plates 10A with separators 10 sandwiched inbetween into a spiral-shape and pressing that spiral roll from bothsides to make it flat. This electrode unit 10 has a spiral structurewith planar sections 10X on both sides connected by U-shaped roundedsections 10Y. This electrode unit 10 is inserted into the case 20 withthe planar sections 10X parallel to the opposing planar surfaces 20A ofthe case 20. When this electrode unit 10 is held in the case 20, it ispressed upon by the opposing planar surfaces 20A of the case 20 withforce that tends to restore it to its original flat spiral-shape.Accordingly, the planar sections 10X of this electrode unit 10 can bepressed with a restoring force by the inside surfaces of the opposingplanar surfaces 20A of the case 20. As a result, the electrode unit 10can be retained in a more immovable fashion via a structure that holdsthe electrode unit 10 with pressure applied by the opposing planarsurfaces 20A of the case 20. However, the power source apparatus of thepresent invention does not limit the battery cell electrode unit to aunit wound in a spiral-shape. This is because a plurality of positiveand negative electrode plates and intervening separators can also be cutin the rectangular-shape of the battery cell opposing planar surfaces,stacked, and held in the case. This type of electrode unit is retainedin the case with electrode plates parallel to the opposing planarsurfaces of the case.

The electrode unit 10 has electrode tabs 31 connected to positive andnegative electrode plates 10A. The electrode tabs 31 are connected tothe positive and negative electrode terminals 32. The battery cell 1 ofFIG. 7 has one electrode tab 31 connected to the current interruptdevice 30, and that electrode tab 31 is connected to the electrodeterminal 32 through the current interrupt device 30. Further, as shownin FIG. 6, the positive and negative electrode terminals 32 areconnected to positive and negative output terminals 32 on the uppersurface of the sealing plate 22. The sealing plate 22 has positive andnegative output terminals 13 attached at both ends of its upper surfacevia insulating material 14. Consequently, positive and negative outputterminals 13 are connected to the internally contained positive andnegative electrode plates 10A, respectively.

Further, the sealing plate 22 that closes-off the open end of theexternal case 21 is provided with an opening 12 for a safety valve 11.The safety valve 11 opens to prevent damage to the case 20 if internalpressure becomes greater than a set value. The set pressure for openingsafety valve 11 is made greater than the set pressure for activatingcurrent interrupt device 30 to cut-off current. Specifically, when theinternal pressure of battery cell 1 rises and exceeds the set pressurefor current cut-off, the deformable metal plate 33 of the currentinterrupt device 30 is deformed by the internal pressure and separatesfrom the connection metal 34 to cut-off current. In this state, batterycell current is cut-off to assure safety. If internal pressure risesfurther with the current interrupt device 30 in the current cut-offstate and becomes greater than the set pressure for opening safety valve11, the safety valve will open. In the battery cells 1, the opening 12of safety valve 11 is provided in the sealing plate 22. This externalcase 21 can discharge gas from the opening 12 of an open safety valve11. This is because gas accumulates inside the case 20. A safety valveopening can also be established on a bottom or side surface of theexternal case. However, when this type of safety valve opens,electrolyte solution is discharged. If electrolyte solution, which is aconducting liquid, is discharged, it can short circuit material that itcontacts. A battery cell 1 with the safety valve 11 established in thesealing plate 22 of the case 20 can reduce internal pressure bydischarging gas from an open safety valve 11. Consequently, when thesafety valve 11 opens, electrolyte solution discharge is restrained anddetrimental effects due to the release of electrolyte solution areminimized.

The power source apparatus of FIG. 1 is provided with gas exhaust ducts18 on top of the car power source apparatus to exhaust gas dischargedfrom the safety valves 11 to the outside. Openings in the bottom of agas exhaust duct 18 connect to safety valve openings 12 to exhaust gasdischarged from the safety valves 11 to the outside. In this structure,gas discharged from a battery cell 1 with an open safety valve 11 can bequickly exhausted to the outside.

A plurality of battery cells 1 are stacked with opposing planar surfaces20A opposite each other to form a battery block 2. Adjacent outputterminals 13 of the stacked battery cells 1 are connected via connectinghardware (not illustrated) to connect the battery cells 1 in series. Inaddition, a wire-lead (not illustrated) is connected to the outputterminals 13 of each battery cell 1. These wire-leads are connected to acircuit board (not illustrated) that implements a protection circuitthat detects battery cell voltage. Although not illustrated, the circuitboard is disposed on top of the car power source apparatus in FIGS. 1and 2.

Spacers 15 are sandwiched between battery cells 1. The spacers 15insulate the external cases 21 of adjacent battery cells 1, andestablish cooling gaps 16 between battery cells 1 to cool the batterycells 1. Consequently, the spacers 15 are formed from insulatingmaterial such as plastic. The spacers 15 are provided with grooves 15Aon both surfaces to establish cooling gaps 16 between adjacent batterycells 1. The spacers 15 are provided with grooves 15A that extend in thehorizontal direction, namely the grooves 15A extend in a direction thatjoins both side-walls of the battery cells 1. Air flows in thehorizontal direction through the cooling gaps 16 established by spacers15 to cool the battery cells 1.

Battery cells 1 are stacked via the spacers 15 and retained in fixedpositions via fastening components 3. The fastening components 3 are apair of endplates 4 disposed at both ends of the stacked battery cells1, and connecting components 5 with end regions connected to theendplates 4 to retain the stacked battery cells 1 in a compressed state.The battery block 2 is held with the endplates 4 disposed at both endsjoined by the connecting components 5 to retain the stacked batterycells 1 with pressure applied in a direction perpendicular to theopposing planar surfaces 20A.

The endplates 4 are made of aluminum or an alloy of aluminum, or theyare molded from hard plastic. The endplates 4 of FIGS. 3 and 4 areprovided with reinforcing ribs 4A extending vertically and horizontallyon the outside surface and formed in single-piece construction with theendplates 4. The bending strength of these endplates 4 is strengthenedby the reinforcing ribs 4A. Endplates 4 with exceptional bendingstrength can effectively prevent expansion at the center regions ofrectangular batteries. This is because battery cell center regionexpansion will not occur as long as the endplates 4 connected byconnecting components 5 do not distort. To sandwich the rectangularbatteries over a wide area, endplates 4 are made with external shapesthat are the same rectangular shape as the rectangular battery cells 1.The rectangular endplates 4 are made the same size as the rectangularbatteries or very slightly larger than the rectangular batteries.Further, the endplates 4 are provided with grooves in the sides oppositebattery cells 1 for cooling air flow, and these grooves establishcooling gaps 16 between the endplates 4 and the rectangular batteries.However, surfaces of the endplates opposite the battery cells can alsobe flat planar surfaces and those planar surfaces can be put in contactwith the surfaces of rectangular batteries or spacers. Plastic endplates4 can be stacked directly on rectangular batteries, while metalendplates are stacked on rectangular batteries via stacking material.

The ends of the connecting components 5 are connected to the endplates4. The ends of the connecting components 5 are connected to theendplates 4 by set screws 6, or the end regions are folded inward toconnect to the endplates, or nuts are threaded on at the ends of theconnecting components, or the ends of the connecting components areconnected to the endplates by snapping or crimping into latches. Anendplate 4 that connects with connecting components 5 via set screws 6is provided with screw-holes 4 a to accept the set screws 6. Thescrew-holes 4 a are provided in the outer surface of an endplate 4, andset screws 6 passing through bent regions 5A of the connectingcomponents 5 are screwed into those screw-holes 4 a to connect theconnecting components 5.

The high voltage battery 9 of FIGS. 3 and 4 has first connectingcomponents 5 disposed along the upper ends of the battery cells 1, whichare rectangular batteries, and second connecting components 5 disposedalong the lower ends of the rectangular batteries connected to theendplates 4. In this high voltage battery 9, screw-holes 4 a areestablished in the upper and lower ends on both sides of the outersurfaces of the endplates 4. This high voltage battery 9 holds the upperand lower parts of the rectangular battery cells 1 with connectingcomponents 5. For connection of the ends of the connecting components 5to the endplates 5 via set screws 6, screw-holes 4 are provided atlocations where the ends of the connecting components 5 attach to theendplates 4.

The connecting components 5 are fabricated from sheet metal formed witha prescribed thickness and prescribed width. The ends of the connectingcomponents 5 connect to endplates 4 to join the pair of endplates 4 andhold battery cells 1 in a compressed state between the endplates 4.Connecting components 5 attach with prescribed dimensions to the pair ofendplates 4 to retain battery cells 1 stacked between the endplates 4 ina prescribed state of compression. If the connecting components 5stretch with battery cell expansion pressure, battery cell expansioncannot be prevented. Therefore, connecting components 5 are made fromsheet metal strong enough to avoid stretching with battery cellexpansion pressure, and are formed with a width and thickness forsufficient strength from stainless steel such as SUS304, steel, or othersheet metal. Further, connecting components can also be formed withside-walls in the shape of channels or rails. Since connectingcomponents with this shape can improve bending strength, they have thecharacteristic that stacked rectangular batteries can be robustlyretained in a prescribed state of compression while reducing theconnecting component width.

A connecting component 5 is provided with bent regions 5A at its ends,and these bent regions 5A are connected to the endplates 4. Set screwthrough-holes are established in the bent regions 5A, and the connectingcomponents 5 are attached to the endplates 4 via set screws 6 insertedthrough the through-holes.

Although not illustrated, a single long connecting component can be bentat its mid-region to connect the bent region around the outer surface ofone endplate and connect both ends to the other endplate. This type ofconnecting component can be sturdily connected to one endplate at itsbent mid-region that loops around that endplate. Further, the connectingcomponent can also be attached to that endplate in single-piececonstruction. This type of connecting component can be attached to oneendplate with maximum robustness.

The car power source apparatus described above is assembled by thefollowing process. The high voltage battery 9 of FIGS. 3-5 is assembledin the following manner.

Battery Block Compression Process

Spacers 15 are disposed between the battery cells 1, which arerectangular batteries. The spacers 15 and battery cells 1 are stacked toform a battery block 2, and endplates 4 are disposed at both ends of thebattery block 2. In this configuration, both endplates 4 are pressed andheld in a holder tool. The unit is compressed until a prescribeddimension is established between the endplates 4, and this configurationis maintained.

Connecting Component Attachment Process

The battery block 2 is retained in the compressed state and both ends ofthe connecting components 5 are attached to the endplates 4. Theconnecting components 5 have bent regions 5A with through-holes providedat both ends. These connecting components 5 are attached to theendplates 4 by screwing set screws 6 inserted through the through-holesin the bent regions 5A into screw-holes 4 a in the endplates 4.

Holder Tool Removal Process

After all the connecting components 5 have been attached to theendplates 4, the holder tool is removed. By the assembly processdescribed above, stacked battery cells 1, which are rectangularbatteries, are maintained in a compressed state between a pair ofendplates 4. Consequently, even if battery cells 1 have a tendency toexpand due to a condition such as over-charging, the distance betweenendplates 4 does not change, and battery cell expansion is prevented bythe endplates 4. In this high voltage battery 9, since both ends of theconnecting components 5 are attached to the endplates 4 by set screws 6,connecting components 5 are robustly connected to the endplates 4, andprescribed dimensions are maintained between endplates 4 via theconnecting components 5. Furthermore, in this state, battery cellelectrode units 10 and current interrupt devices 30 are retained withpressure applied by opposing planar surfaces 20A of the cases 20.Therefore, there is no movement of the electrode units 10 or the currentinterrupt devices 30 due to vibration, and relative motion between anelectrode unit 10 and current interrupt device 30 to separate theconnection region and cut-off current is prevented.

It should be apparent to those of ordinary skill in the art that whilevarious preferred embodiments of the invention have been shown anddescribed, it is contemplated that the invention is not limited to theparticular embodiments disclosed, which are deemed to be merelyillustrative of the inventive concepts and should not be interpreted aslimiting the scope of the invention, and which are suitable for allmodifications and changes falling within the spirit and scope of theinvention as defined in the appended claims. The present application isbased on Application No. 2008-335518 filed in Japan on Dec. 27, 2008,the content of which is incorporated herein by reference.

What is claimed is:
 1. A car power source apparatus comprising: a highvoltage battery having a plurality of battery cells connected in seriesor in parallel, each of the battery cells having a case, a currentinterrupt device housed in the case, and an electrode terminal connectedto the current interrupt device, the current interrupt device beingdeformable to separate a connection point and cut-off current wheninternal pressure of the battery cell exceeds a set pressure, andwherein: each of the cases has a rectangular outline with a pair ofopposing planar surfaces, and an electrode unit, which is a stack ofpositive and negative electrode plates with intervening separators, thecurrent interrupt device is disposed between the pair of opposing planarsurfaces, the plurality of battery cells is stacked with opposing planarsurfaces opposite each other to form a battery block, a pair ofendplates is disposed at the ends of the battery block, the pair ofendplates is connected by connecting components, and the pair ofendplates holds the battery cells in the stacked configuration so as toapply pressure in a direction perpendicular to the opposing planarsurfaces, and the electrode unit is disposed inside the opposing planarsurfaces of the case so that the electrode unit is pressed with arestoring force by inside surfaces of the opposing planar surfaces ofthe case so that the electrode unit and the current interrupt device areheld in the case in a stationary manner so as to prevent vibration. 2.The car power source apparatus as cited in claim 1, wherein the currentinterrupt device is provided with a deformable metal plate that isdeformable in response to battery cell internal pressure, and connectionmetal that locally connects electrically to the deformable metal plate;wherein, when battery cell internal pressure becomes greater than theset pressure, the deformable metal plate deforms due to pressure anddetaches from the connection metal to cut-off current.
 3. The car powersource apparatus as cited in claim 2, wherein the deformable metal plateis a diaphragm formed in a curved arch-shape, and a peak region of thediaphragm is welded to the connection metal for electrical connection.4. The car power source apparatus as cited in claim 3, wherein thediaphragm is connected to the electrode terminal, and the connectionmetal is connected to an electrode tab that is connected to an electrodeplate.
 5. The car power source apparatus as cited in claim 3, whereinthe current interrupt device houses the diaphragm and the connectionmetal in an inner case made of insulating material.
 6. The car powersource apparatus as cited in claim 5, wherein the inner case joins oneside of the diaphragm with the inside of the battery cell, and seals-offthe other side of the diaphragm in an airtight fashion.
 7. The car powersource apparatus as cited in claim 3, further comprising a cover plateattached in an air-tight fashion to one side of the diaphragm tohermetically seal-off the one side of the diaphragm.
 8. The car powersource apparatus as cited in claim 7, wherein the cover plate and thediaphragm are shaped as disks, and a peripheral rim of the cover plateand a peripheral rim of the diaphragm are attached in an airtightfashion.
 9. The car power source apparatus as cited in claim 1, whereinthe current interrupt device is connected between the electrode terminalof the battery cell and the electrode unit housed in the case.
 10. Thecar power source apparatus as cited in claim 1, wherein each of thebattery cells is provided with a safety valve that opens when internalpressure of the battery cell becomes greater than a set pressure, andthe set pressure for safety valve opening is set greater than thepressure for current cut-off by the current interrupt device.
 11. Thecar power source apparatus as cited in claim 1, wherein the electrodeunit has positive and negative electrode plates and interveningseparators stacked and wound in a spiral-shape with planar sections andU-shaped rounded sections, and the electrode unit is disposed in thecase with the planar sections parallel to the opposing planar surfacesof the case.
 12. The car power source apparatus as cited in claim 1,wherein the case is a metal case, and insulating material is providedbetween the inside surfaces of the case and conducting regions of thecurrent interrupt device.
 13. The car power source apparatus as cited inclaim 1, further comprising an insulating material located on at least apart of the inside surfaces of the opposing planar surfaces of the casewherein the case is a metal case, and the insulating material isinterposed between the electrode unit and the part of the insidesurfaces of the opposing planar surfaces of the case to establishnon-electrical contact therebetween.
 14. The car power source apparatusas cited claim 1, wherein the endplates are provided with reinforcingribs extending vertically and horizontally on an outside surface thereofand the reinforcing ribs are formed in single-piece construction withthe endplates.
 15. The car power source apparatus as cited claim 1,wherein an outline of the endplates is made in a rectangular shape thatis the same rectangular shape as the shape of the rectangular cases ofthe battery cells.
 16. The car power source apparatus as cited in claim15, wherein the rectangular endplates are the same size as therectangular cases of the battery cells or are slightly larger than therectangular cases of the battery cells.
 17. The car power sourceapparatus as cited claim 1, wherein the connecting components are sheetmetal with a prescribed width and thickness.
 18. The car power sourceapparatus as cited claim 1, wherein ends of the connecting componentshave bent regions attached to the endplates.
 19. The car power sourceapparatus as cited in claim 18, wherein the bent regions havethrough-holes receiving set screws, and the connecting components areattached to the endplates via set screws inserted in the through-holes.20. The car power source apparatus as cited claim 1, wherein the batterycell has the current interrupt device housed in an upper section of thecase, the connecting components are connected to upper and lowersections of the endplates, and upper sections of the pair of endplatesare pulled together by the connecting components to retain the batterycells with pressure applied to upper sections of the end plates.